It is reported that around 20 of the boys' friends attended the party, along with Britney, her fiancé Jason Trawick and father Jamie Spears. It is not yet known if the children's father, Kevin Federline, was in attendance.

A source told E! news: "Britney was smiling ear-to-ear during the whole party and enjoyed watching her kids play with their friends.

"It was a really lovely occasion; everyone was in a good mood and in the spirit of the birthday."

They added: "She looked overjoyed and at one point was singing happy birthday to them. Jason and Britney were beaming and couldn't have been more proud of Jayden James and Sean Preston."